Metal based drinking water pipes and fittings such as those formed using lead and copper are known to leach toxic materials such as lead and copper into the drinking water supply. The presence of lead and other metals in drinking water poses a range of risks to human health, including the retardation of some aspects of child development, the inducement of abortion, and other clinical disorders. The extent of these risks has not been quantified at the European Union (EU) scale. A number of sampling methods are in use in the EU, the United States and Canada, some of which are inadequate for determining the concentrations of lead in drinking water at consumers' taps. The new legal standard requirement in the EU starting in 2013 will require that lead amounts in drinking water up to the point of delivery at the consumers building cannot exceed 10 μg/L (10 ppb (parts per billion).
The non-compliance with the EU standards for lead in drinking water has been under-estimated. Emerging data on existing lead and copper based water pipes in some European Union countries indicates significant non-compliance with these standards in, particularly with the 10 μg/L (10 ppb (parts per billion) standard that will become a legal requirement in 2013. In addition the current interim standard of 25 μg/L (25 ppb) is also exceeded in some locations.
An initial estimate is that 25% of domestic dwellings in the EU have a lead pipe, either as a connection to the water main, or as part of the internal plumbing, or both, potentially putting up to approximately 120 million people or more at risk from lead in drinking water within the EU.
Current corrective remedies include the use of chemical additions to the water supply such as dosing with phosphate-based materials, conventional dig and replace methods, pull through, moling or slip lining methods and the use of internally placed resin based coatings.
Internally placed resin based coatings have thus far presented a non-economical solution to the problem of reducing lead levels to the less than the new 10 μg/L (10 ppb) standard. Current coating processes and techniques usually require long cure times and potential leachates coming from the coating especially when the coatings are subject to high surface area of pipe wall to water volume in small diameter piping systems. For example, pipes less than approximately 50 mm (2″) in diameter and are tested accordingly for leachates.
It is common that the internal diameter of service pipes range from approximately 12 mm (½″) to approximately 50 mm (2″) ie, having high surface area of pipe wall to water volume. In order to not restrict the flow of the liquid through the coated small diameter pipe, that is pipes that have an interior diameter, ID, in the ranges of approximately 12 mm (½″) to approximately 50 mm (2″), the placed linings typically range in thickness from an average of approximately 100 microns (4 mils) to approximately 400 microns. (16 mils) Thin set linings, in more or less the above stated range of thickness, can be prone to the application problem of pin holing occurring in the uncured coating as well as being contaminated with free lead particulates during the application and curing stage, making compliance to the 10 μg/L (10 ppb) maximum lead content in drinking water standard difficult and potentially impossible to achieve. This invention overcomes these problems.
The use of compression fittings, in-line connectors or couplings and in-line valves are common in the industry. However, when these in-line connectors and valves are used, pipe ends and exterior portions of the pipe within the fittings maybe left exposed, leaving direct water to metal contact.
In the United Kingdom, products that come into contact with public drinking water must conform to various regulations including Drinking Water Inspectorate Regulation 31. Regulation 31 of the Water Supply (Water Quality) Regulations 2000 implements Article 10 of the Council of the European Union Drinking Water Directive (DWD) in England and Wales for all chemicals and construction products used by water undertakers, from the source of the water, up to the point of delivery to the consumer's building. This regulation sets out how approvals can be given to such construction products and materials that do not prejudice water quality and consumer safety.
Article 10 of the DWD requires Member States shall take all measures necessary to ensure that no substances or materials for new installations used in the preparation or distribution of water intended for human consumption or impurities associated with such substances or materials for new installations remain in water intended for human consumption in concentrations higher than is necessary for the purpose of their use and do not, either directly or indirectly, reduce the protection of human health. Under Article 10, the interpretative document and technical specifications pursuant to Article 3 and Article 4 (1) of Council Directive 89/106/EEC of 21 Dec. 1988 on the approximation of laws, regulations and administrative provisions of the Member States relating to certain construction products shall respect the requirements of this Directive.
Piping systems, valves and fittings such as those used as communication and supply lines servicing buildings and within commercial buildings, apartment buildings, condominiums, as well as homes and the like that have a broad base of users that may be exposed to water that may be tainted by the leaching of metals such as lead and copper that have leached into the water supply at levels deemed to pose possible health concerns is the target of this invention.
Present corrective remedies include the use of chemical additions to the water supply such as dosing with phosphate-based materials, conventional dig and replace methods, pull through, moling or slip ling and the use of internally placed resin based coatings. When internally placed coatings are used they attempt to coat the interior of the pipe but leave pipe ends uncoated, internal fittings uncoated and the exterior of pipe sections that lay within internal fittings areas that are exposed to drinking water, uncoated. These uncoated areas when exposed to drinking water will continue to leach metals such as lead and copper into the water supply.
Corrective measures taken by adding phosphates to the drinking water to reduce lead from leaching from substrate materials is presently a common practise in the United Kingdom (UK). However, phosphates have been identified as being scarce and resources are being depleted rapidly on a worldwide basis.
The UK places phosphate into the public water supply to reduce plumbosolvancy (dissolution of lead from old pipework) and has used phosphate dosing ranges from 0.5-1 mgP/L in low alkalinity areas to 1-1.5 mgP/L in high alkalinity areas. Most water is dosed with phosphate because it is currently not practicable to target properties with lead supply or internal plumbing. Taking 1 mgP/L as an average and 17395 ML/day into supply equates to about 15,000 tP2O5/y. To put this in context, the UK's Department for Environmental, Food and Rural Affairs (Defra (2011)) reports the total phosphate fertiliser use in the UK is about 200,000 tP2O5/y. There are additional problems with using present thermoset resin based coating systems. It is widely known that thermoset resin based coating systems do not readily complete cure at ambient temperatures, leaving un-reacted organic moieties and complexes available for water extraction or leaching. This leaching can be further compounded with the use of chlorinated water.
Thus, the need exists for a solution to deliver a protective coating system that protects the pipe and fittings, from the effects of corrosion and reducing metals from unacceptable levels from leaching into the water supply, without the need to fully disassemble the pipe from the fittings wherein the coating is placed in a single coat operation. A further need exists wherein the use of phosphates used, in dosing the water to reduce lead and metals leaching, can be reduced or replaced, thereby reducing demand on this scarce and depleting resource.
Present methods to accelerate the cure of lining materials, once placed inside a pipe may involve the use of hot water or steam circulated through the piping system. In these present systems the coating is separated from the steam or water by a flexible membrane or the water curing stage is initiated only after the coating has reached its B stage of curing.
U.S. Pat. Nos. 5,622,209 and 5,007,461 and 5,499,659 to Naf each generally require long pipe system down times before piping systems can be returned to service. Generally, the patents describe methods that include “blowing through” the coating in which air was left to stream over the uncured coating “for a further 30 minutes, and the conduit was sealed at the top and bottom at the end of the blowing period. Two days later, the conduit was reconnected to the network and thoroughly flushed beforehand.” The Naf patents refer to adducts but not phenol free and plasticizer free amine adducts added to the curing agent. There is no mention in these references of curing with water or moisture contact. Phenol free and plasticizer free amine adducts were not commercially available at the time of the 1988 to 1995 filing dates of the Naf patents.
The Pasteur Document dated 2002, associated with Naf, references a 48 hour cure time.
U.S. Pat. No. 5,707,702 to Brady describes a coating having a pot life (working time not cure) of 1-4 hours and in the embodiment says left to cure for 24 hours. These embodiments do not describe the use of phenol free and plasticizer free amine adducts.
There is no mention in these references of curing with water or moisture contact.
U.S. Pat. Nos. 7,160,574 and 7,517,409 and U.S. Pat. Nos. 7,858,149, 8,033,242 and 8,026,783 to Gillanders et al, assigned to the same assignee as the subject invention, which are incorporated by reference, describe pipe coating systems and methods that all refer to restoring piping systems to services within times from less than 24 to 96 hours, but do not reference the use of phenol free and plasticizer free amine adducts added to the curing agent or using water or steam, in the curing stage.
U.S. Pat. Nos. 6,739,950 and 7,041,176 to Kruse do not mention the use of phenol free and plasticizer free amine adducts added to the curing agent or water cure of the barrier coatings. Curing requires at least day long cure times and high cure temperatures. For example, Kruse '176 describes a 24 hour time period for curing their coatings. Additionally, each of the Kruse references require high heat on pipe 100-120° F. (38-49° C.), while the subject invention requires substantially lower air temperatures while yielding much quicker cure times.
The U.S. Navy Research Document 1997, entitled: Control of Lead in Drinking Water, epoxy requires 12-18 hours of hot air to cure and, no mention of using moisture to cure. Furthermore, there is no mention of the use of phenol free and plasticizer free amine adducts added to the curing agent.
The U.S. Military Standard, 2001—Public Works Bulletin 420-49-35 requires 24 hour cure with 75° F. (24° C.) air, there is no mention of using moisture while curing the coating and there is no mention of the use of phenol free and plasticizer free amine adducts added to the curing agent.
U.S. Pat. No. 4,966,790 to Iizuka describes examples which show long time lines to cure, with a minimum of 24 hours of air cure prior to a water cure stage. None of the curing agents describe the use of phenol free and plasticizer free amine adducts, no disclosure of toxicological data. The epoxy described in Iizuka, after 24 hours, prior to the water curing stage would have passed its plastic state ie A-Stage of curing.
U.S. Pat. No. 8,053,031 to Stanley describes the use of an anhydride introduced into the resin, which is not the use of a phenol free and plasticizer free amine adduct added to the curing agent as the subject invention practices. Stanley '031 describes in Table 1 contained in the '031 patent, using a measurement of BPA being leached from the cured epoxy after 2 days at 100 μg/L (100 ppb) and at 20 μg/L (20 ppb) in the 2 examples given. This reference makes no mention of epichlorohydrin or TOC levels, which is required under current regulations, there is also no data to demonstrate the effects of the coating over a lead substrate.
U.S. Published Patent Application 2010/0266764 to Robinson et al. describes a polyurethane coating technique for pipe lining, which has a rapid setting of 3 to 6 minutes. However, this process would not result in coating all of the interior surfaces of the pipes, as well as causing clogs inside the pipe because it sets so quickly. This type of coating cannot pass through intersections and valves and fittings without clogging. Also, polyurethane based coatings are not known to meet toxicology requirements for small diameter drinking water pipes (such as those having an ID of 2 inches (or 50 mm)) or less in size, that can be placed in-situ and returned to service having contact with potable water within 12 hours or less.